In the case of fuel injectors already known, fuel filters are press-fit into a fuel intake nipple and, thus, secured in place in it. This manner of fastening involves the risk of dust and cuttings forming, which can lead to the malfunction of the fuel injector. In addition, retaining collars for upper sealing rings are constructed as individual component parts.
A fuel injector, in which a fuel filter is manufactured in one piece with a retaining collar, is already known from German Published Patent Application No. 43 25 842. The retaining collar radially extends beyond the fuel intake nipple and has a lip outside the fuel intake nipple. The circumferential lip of the retaining collar forms, together with a groove on the outer circumference of the fuel intake nipple, a snap-in connection, by which the fuel filter is fastened in a defined manner. There is only a clearance fit between the base of the fuel filter and the inner wall of the fuel intake nipple, so that any build-up of shavings in the interior of the fuel injector is prevented.
In addition, European Patent No. 0 697 064 describes a filter, which is for a fuel injector having central fuel delivery and is form-locked to an adjusting sleeve for a restoring spring that keeps the fuel injector closed in the rest state. In this context, the filter is made out of a plastic frame, over which a mesh grating is laid. The filter is connected to the adjusting sleeve with the aid of a snap-in fastener, the adjusting sleeve preferably being made of metal. This allows the static rate of flow through the fuel injector to also be calibrated after the filter is inserted.
A particular disadvantage of the fuel injectors known from the above-mentioned, printed publications is the large amount of processing time spent in attaching the filter to either the adjusting sleeve or the fuel intake nipple. In addition, the filter and adjusting sleeve are made of different materials, whereby cuttings and dust are formed at the contact surfaces, predominantly on the plastic of the filter, which can lead to the malfunction of the fuel injector caused by the deposition of the particles.